Abiotic stress results in significant reductions in crop yield and quality world-wide. Drought, ozone, salinity, toxic metals and extremes in temperature are just a few of the examples of the types of abiotic stresses to which plants are exposed. Two of these stresses, drought and salinity, are widespread in many regions. It is estimated that by the year 2050, more than 50% of all arable lands will be severely affected by salinity. In the face of a global scarcity of water resources and the increased salinization of soil, plant biotechnologies aimed at genetically improving plants to enhance their adaptation to environmental stresses need to be identified and implemented.
In recent years, with the significant advances made in the area of genomics, genetic regulators related to plant stress tolerance have been identified, which may have the potential to be utilized in crop improvement through genetic engineering. One example of such genetic regulators are microRNAs (miRNAs). MicroRNAs are a class of noncoding small RNAs which originate from pri-miRNA transcripts that are encoded by miRNA genes. The pri-miRNA transcripts are processed into smaller 19-24 nucleotide RNAs, which can regulate gene expression, for example, through silencing reactions by translational inhibition or cleavage.
The present invention provides methods and compositions employing miRNAs and small interfering RNAs (siRNA) to enhance abiotic tolerance in plants.